This invention relates to tube bending tools and more particularly to manually operable tube benders especially suited for effecting bends of in excess of 90 degrees.
Manually operated tools for bending tubing are quite old and well known in the art. For example, such tools are widely used by electricians for forming bends in an electrical conduit. Examples of commercial tube benders sold by Stride Tool Inc. and its predecessors are described and claimed in U.S. Pat. Nos. 4,379,399, 4,380,922, 4,289,872, 4,389,873, 4,403,496, 4,379,400, and 4,424,699 (herein the Stride Patents). With the tools of the Stride Patents bends up to 180 degrees may be accomplished. While the tools have enjoyed longstanding commercial success, the tools are somewhat awkward for use in effecting bends in excess of 90 degrees because the handles which are manipulated by an operator to effect the bend cross over when a tube is being bent beyond 90 degrees. When the handles cross over manipulation becomes somewhat awkward and difficult. Moreover, an operator in bringing his hands toward one another through the first 90 degrees while after the cross over an operator""s force application is reversed and one is pulling one""s hands apart or pressing with crossed arms.
Another tool that has been available commercially for a period of time requires disconnection of one of the handles after a 90 degree bend has been completed by unscrewing the handle from the tool element to which it is connected. The handle is then reconnected by threading it into other threaded recess to effect bending from 90 degrees up to 180 degrees. With at least one other commercially available tool there is no provision for bending beyond 90 degrees.
Accordingly it would be desirable to produce a manually operated tube bender which is capable of effecting bends up to 180 degrees without handle cross over or the need to disconnect and reconnect one of the handles after 90 degrees of bending has been accomplished.
With the tool of the present invention, a mandrel corresponding to the mandrel described and claimed in the Stride Patents is provided. The mandrel has a tube engaging recess which has an arcuate configuration in cross section and itself is a semi circle in its other plane of cross section to provide tube support for bending up to 180 degrees. A link is connected to the mandrel for rotation about the mandrel axis. A forming member is pivotally connected to the link in spaced relationship with the mandrel axis such that forming rollers carried by the forming member engage a tubular work piece mounted in engagement with the mandrel and held in place by a hook retainer. A pair of manually operated handles are respectively connected to the mandrel and the forming member for manipulative application of forces to a tubular work piece to bend the work piece.
With the tool of the present invention the forming member handle includes an obtuse bend such that gripping portions of the handles are located in a manner which facilitates effecting the first 90 degrees of bending. If a work piece is to be bent in excess of 90 degrees the forming member handle is rotated relative to its mounting in the forming member to relatively reposition the handles until gripping portions of the handles are appropriately located for facilitating further bending of the tube beyond 90 degrees.
A latching mechanism is provided to fix the handle selectively and one at a time in its under 90 and over 90 degree bending positions. The latching mechanism in the preferred and disclosed arrangement is a spring biased, reciprocal rod which is axially shiftable between handle lock and handle release positions. The latching mechanism retains a handle in its under 90 or over 90 bending positions selectively and one at a time or alternately permits ready rotation of the forming member handle relative to the forming member.
Accordingly the objects of the invention are to provide a novel and improved tube bender and a method of bending tubes.